/*
 * Copyright (c) 2011-2025 PiChen
 */

/*
 * The Spring Framework is published under the terms
 * of the Apache Software License.
 */

package com.interface21.ejb.support;

import javax.ejb.CreateException;
import javax.ejb.MessageDrivenBean;
import javax.ejb.MessageDrivenContext;

/**
 * Convenient superclass for MDBs.
 * Doesn't require JMS, as EJB 2.1 MDBs are no longer
 * JMS-specific: see the AbstractJmsMessageDrivenBean subclass.
 * <p>
 * <p>This class ensures that subclasses have access to the
 * MessageDrivenContext provided by the EJB container, and implement
 * a no argument ejbCreate() method as required by the EJB specification.
 * This ejbCreate() method loads a BeanFactory, before invoking the
 * onEjbCreate() method, which should contain subclass-specific
 * initialization.
 * <p>
 * <p>NB: We cannot use final methods to implement EJB API methods,
 * as this violates the EJB specification. However, there should
 * be no need to override the setMessageDrivenContext() or
 * ejbCreate() methods.
 *
 * @author Rod Johnson
 * @version $Id$
 */
public abstract class AbstractMessageDrivenBean
        extends AbstractEnterpriseBean
        implements MessageDrivenBean {

    /**
     * MessageDrivenContext passed to this object
     */
    private MessageDrivenContext messageDrivenContext;

    /**
     * Required lifecycle method. Sets the MessageDriven context.
     *
     * @param messageDrivenContext MessageDrivenContext
     */
    public void setMessageDrivenContext(MessageDrivenContext messageDrivenContext) {
        logger.debug("setMessageContext");
        this.messageDrivenContext = messageDrivenContext;
    }

    /**
     * Convenience method for subclasses to use.
     *
     * @return the MessageDrivenContext passed to this EJB by the EJB container
     */
    protected final MessageDrivenContext getMessageDrivenContext() {
        return messageDrivenContext;
    }

    /**
     * Lifecycle method required by the EJB specification but not
     * the MessageDrivenBean interface.
     * <p>This implementation loads the BeanFactory. Don't override it
     * (although it can't be made final): code your initialization in
     * onEjbCreate(), which is called when the BeanFactory is available.
     * <p>Unfortunately we can't load the BeanFactory in setSessionContext(),
     * as ResourceManager access isn't permitted and the BeanFactory may require it.
     */
    public void ejbCreate() throws CreateException {
        loadBeanFactory();
        onEjbCreate();
    }

    /**
     * Subclasses must implement this method to do any initialization
     * they would otherwise have done in an ejbCreate() method. In contrast
     * to ejbCreate, the BeanFactory will have been loaded here.
     * <p>The same restrictions apply to the work of this method as
     * to an ejbCreate() method.
     *
     * @throws CreateException
     */
    protected abstract void onEjbCreate() throws CreateException;

}
